The present invention relates generally to the making of electrical signal connections between circuit boards and, more particularly, to a technique for interconnecting a port card and a switch card without using a midplane.
In many computer systems, electronic components are typically mounted on a plurality of circuit boards. These circuit boards, often referred to as port cards, are typically mounted on a switch card so as to allow electrical connections to be made between the electronic components mounted on the port cards. The mounting of the port cards on the switch card is typically accomplished through conventional pin-and-box connectors, and through the use of additional circuit boards (commonly referred to as midplanes) in instances where an orthogonal interconnection between switch and port cards is desired. However, there are intrinsic and mechanical related parasitics associated with these conventional methods. These parasitics put limits on maximum signal transmission bandwidth across the switch and port cards. In fact, the best connector that is presently known in the industry claims to be able to handle 5 Gb/s, which cannot meet the bandwidth demands associated with new telecommunication systems, which are on the order of 10 Gb/s.
There are also space concerns associated with the use of conventional pin-and-box board-to-board connectors. That is, conventional pin-and-box board-to-board connectors typically have bulky mechanical shrouds which take up valuable board and shelf space. Also, the use of midplanes in prior art interconnections prevents proper airflow over the port and switch cards.
In view of the foregoing, it would be desirable to provide an improved electrical interconnection between circuit boards which overcomes the above-described inadequacies and shortcomings. More particularly, it would be desirable to provide a technique for interconnecting a port card and a switch card without using a midplane, while eliminating problems associated with mechanical electrical connectors.
According to the present invention, an improved electrical interconnection between a first circuit board and a second circuit board is provided. In one embodiment, the first circuit board has a substantially rigid circuit portion having a plurality of circuit layers, including a first signal layer, and a first interconnection portion, including the first signal layer, for mating with a second interconnection portion of the second circuit board. The first circuit board also includes a flexible portion, including the first signal layer, for connecting the substantially rigid circuit portion to the first interconnection portion. The flexible portion allows the first interconnection portion to be oriented substantially perpendicular to the substantially rigid circuit portion such that a mating of the first interconnection portion with the second interconnection portion results in a substantially orthogonal electrical interconnection arrangement between the first circuit board and the second circuit board. In conventional architecture such orthogonal arrangement requires a midplane.
In accordance with further aspects of the present invention, the mating is accomplished through a direct electrical connection consisting of a male connector connected to the first interconnection portion and a female connector connected to the second interconnection portion for receiving the male connector, and vice-versa.
In accordance with further aspects of the present invention, the mating is accomplished through electromagnetic coupling.
In accordance with still further aspects of the present invention, at least one dielectric constant material is beneficially disposed between the first circuit board and the second circuit board in the area where the first opening and the second interconnection portion are aligned.
In accordance with still further aspects of the present invention, the first circuit board may be a switch card, and the second circuit board may be a port card.
The present invention will now be described in more detail with reference to exemplary embodiments thereof as shown in the appended drawings. While the present invention is described below with reference to preferred embodiments, it should be understood that the present invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the present invention as disclosed and claimed herein, and with respect to which the present invention could be of significant utility.